Researcher

John Hunyara

Objective

To determine the solubility of trans-cinnamic acid in methanol by the density method.

Results

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Molarity was determined for the solution of methanol and cinnamic acid in each of the 3 volumetric flasks:
5 mL flask: 1.81 M
2 mL flask: 1.67 M
1 mL flask: -0.02 M (error)

Discussion

The range of molarity for this experiment was 1.67-1.81 M. The value recorded for the 1 mL flask produced a negative answer, implying a mass measurement error. Past results gave a range of 1.3-1.52 M. The values measured for this experiment were slightly outside the expected range from past experiments. A molarity of 1.431 M is the accepted value for the solubility of cinnamic acid in methanol. Contaminants or measurement error on the weigh scale may have caused values out of the range.

Conclusion

Although densities were recorded, the values for the 5 mL flask and the 2 mL flask were slightly above the accepted molarity of 1.431 M. The value for the 1 mL flask was calculated through an error and is not even logical.

Log

2011-01-25
14:05

14:06 - Water bath turned on to 40 C.
14:11 - 5.91 grams of trans-cinnamic acid were measured into a 20 mL tube. Methanol was added to fill up the majority of the tube, leaving some space at the top.
14:48 - Temperature in the bath was at 42 C. Solution was placed in bath at this time.
14:58 - Dry volumetric flasks of 5 mL, 2 mL, and 1 mL were used to measure densities of pure methanol.
15:45 - Another water bath was set up. Temperature was at 23 C.
16:10 - Bath temperature was at 40 C. Tube was removed.
16:12 - Supernatant was decanted and placed in another 20 mL tube. At this time the new tube was placed in the 23 C bath. Crystallization occurred.
16:35 - Tube was removed from 23 C bath and supernatant was again removed.
16:38 - Dry volumetric flasks of 5 mL, 2 mL, and 1 mL were used to measure densities of the methanol/cinnamic acid solution.